[geeks] Has anyone used power-line communications?

[gsm at mendelson.com]

On Sat, Jul 30, 2011 at 02:46:06PM -0500, Bob wrote:
>Hmmm. was the DSL interfering with the radio or the radio interfering
>with
>the DSL?  I had no problems here either way and my antennas were on the
>house.  I usually never ran more than 100 watts out so that might not
>have had
>an effect.  Since the BPL signal leaked out of the power line, I always
>wondered
>if some ham fired up his kw, turned his beam so the power lines were in
>the
>line of fire, would the kid down the street have trouble playing WoW?
>Never saw that addressed.

No, the problem is that DSL uses telephone lines to carry HF signals. 
Pretty much the same way that BPL does, e.g. multiple carriers at different
speeds. In fact, it would be accurate to look at BPL as DSL over power lines
instead of telephone lines.

In the old days DSL lines were low frequency, such as 1.5mbit, so they did 
not produce much more noise above 3mHz. Now that they are much faster, 
my aDSL line is 880k up (noise in the AM band) and 15mbit down (noise
up to 30mHz and harmonics). 

FIOS has eliminated that, but many places don't have FIOS. I have fiber to
a common point about 100 meters from my home, and then unshielded telephone
wire to my router.

In some ways it's a moot point, someone at a telco is going to figure out how
to get the taxpayers to fund a bond issue for "infrastructure" and rip out 
all of the copper wire so they can sell it a high price and replace it with
fiber which is made from plastic covered sand. :-)

As for the ham causing DSL to crash, not likely. The devices use adaptive
technology and if a band is unsuable, switch to another one. That was the
big selling point of BPL, it could be programmed to avoid the narrow bands
that are allocated to hams, rendering their resistance moot. However no one
actually trusted a power company employee to not squeeze a little extra
bandwidth by turning them on. :-(

Geoff.

-- 
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.